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Pohang, South Korea

Kim J.,Korea Railroad Research Institute | Lee K.-S.,Korea Railroad Research Institute | Oh J.-G.,Corechips
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering | Year: 2011

This study aimed to replace the current discontinuous rail monitoring system by applying "Plug and Play" technology to rail system monitoring to enable real-time monitoring, and by confirming on-condition maintenance efficiency and reliability. It examined a wireless sensor monitoring system which uses SAW (Surface Acoustic Wave) technology to monitor temperature changes in the axle box bearing of railroad vehicles during operation. The results of the experiment were compared with HDB measurements to confirm the reliability of the real-time monitoring results measured on vehicles during operation. © 2011 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering. Source


Lee J.,Sogang University | Kim S.,Sogang University | Oh J.,Corechips | Choi B.,Sogang University
International Journal of Automotive Technology | Year: 2012

Tire intelligence is vital in the improvement of the safety of vehicles because the tire supports the car body and is the contact point between the vehicle and the road. To create an intelligent tire, sensors must be installed to measure the behavior of the tire. However, it is difficult to apply a wired sensor system on the wheel of the tire. Hence, it is necessary to implement a self-powering, wireless system (a type of energy harvesting system) that can be mounted inside the tire. The purpose of this study is to convert the strain energy caused by deformation of the tire while driving into useful electrical energy to supply the sensor system. A flexible piezofiber is utilized for the energy conversion. The variation in strain, due to changes in speed, load, and the internal pressure of the tire, was measured along two axial directions to evaluate the amount of available strain energy. The amount of strain changed from 0.15% to 0.8%. To predict the amount of available energy from a tire, we perform an analysis of the relationship between the strain and the voltage. In addition, experiments for impedance matching between piezofiber and related circuits were conducted to optimize the external loads for transferring energy efficiently. Based on the procedure mentioned above, at least 0.58 mJ of electrical energy can be generated by using the laterally oriented strain (1500 to 2500 micro strain). The result of this study is expected to enhance the potential realization of self-generating wireless sensor systems for so-called "intelligent" tires. © 2012 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg. Source


Lee J.,Corechips | Choi B.,Sogang University
Energy Conversion and Management | Year: 2014

The need for energy harvesting technology is steadily growing in the field of self-powered wireless sensor systems for intelligent tires. The purpose of this study is to mount an energy harvester inside the tire. In order to achieve this, we focus on a stable energy source almost independent of vehicle speed. It is ascertained that the use of a strain field is suitable for this purpose. In order to develop the energy harvester for the tire, modeling of tire behavior has been performed and verified through comparing with experimental results. From the results, a piezoelectric energy harvester generates 380.2 μJ per revolution under 500 kgf load and 60 km/h. A self-powered wireless sensor system is manufactured for application and tested during vehicle driving. The result of this study presents 1.37 μW/mm3 of power generation from the performance of the energy harvester. This study concludes that the system is applicable to wireless tire sensor systems after making minor improvements. © 2013 Elsevier Ltd. All rights reserved. Source


Lee J.,Corechips | Oh J.,Corechips | Kim H.,Randnter | Choi B.,Sogang University
Journal of Intelligent Material Systems and Structures | Year: 2015

Vehicle safety can be improved by tire pressure monitoring with a wireless sensor system. Since a battery-powered wireless sensor system for tire pressure information is limited by the life of the battery, energy harvesting technology is applied. In order to develop an energy harvester based on a piezoelectric material for the tires, modeling of tire behavior and the energy harvester, and the validation of the modeling were performed. The structural behavior of a tire was numerically modeled and verified by comparing the simulation results with experimental data. In order to compare the generated voltages between the modeling and the experiment, comparisons of the root-mean-square voltage values for various velocities and loads, the distortion factor using the root-mean-square value of the wave form, and the crest factor for verifying the efficiency of the peak value of the wave form were conducted. The results showed that the differences are on average 10% for the loads between 300 and 700 kgf and velocities between 20 and 60 km/h (430 r/min). For the improvement of the energy harvester's performance, the thickness of substrate was controlled and the generated voltage was increased. If a sensor for measuring radius is applicable to the tire, the strain on the tire can be collected, and thus the loads applied to the tire can be estimated. With a wireless sensor system for measuring radius driven by energy harvesting, we can be one step closer to the embodiment of an intelligent tire. © The Author(s) 2014. Source


Park K.,MANDO Corporation | Oh J.,Corechips
SAE Technical Papers | Year: 2013

Although tire forces are important as factors governing the behavior of a vehicle, current chassis control systems have used tire forces indirectly estimated. Hence, this research developed Intelligent Tire System (i-Tire) that can measure tire forces directly. This system used a deform gage and a surface acoustic wave (SAW) sensor, which are capable of passive radio communication. The performance of this developed system was tested with a tire test system (MTS Flat Trac) and a vehicle test. Copyright © 2013 SAE International. Source

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